C ++，数组-Windows错误当机，但没有编译器错误

Question

Ok so here's my code. I'm getting no errors in the compiler, however when I run this program it lets me input 2 names then crashes with a Window's Error. What in the heck am I doing wrong?!

#include <iostream>

using namespace std;

//declaration of variables

int i; // Loop Counter
int x; // Number of Family Members

int main()
{

string FamilyName[x]; // Array of Names


cout << "Enter Number of Family Members" <<endl;
cin >> x;

for (i = 0 ; i < x ; i++){
        cout << "Enter Family Member's Name: " <<endl;
        cin >> FamilyName[i];
}
for (i = 0 ; i < x ; i++){
    cout << FamilyName[i] <<endl;
}

return 0;
}

Answer 1

You can solve the problem in two ways, allocate the array to a large size(x should be initialized...and it should be a constant value) and then the code becomes:

#include <iostream>
#include <string>
using namespace std;

//declaration of variables

int i; // Loop Counter
const int x = 500; // MAX Number of Family Members

int main()
{

string FamilyName[x]; // Array of Names

int count;
cout << "Enter Number of Family Members" <<endl;
cin >> count;

for (i = 0 ; i < count ; i++){
        cout << "Enter Family Member's Name: " <<endl;
        cin >> FamilyName[i];
}
for (i = 0 ; i < count ; i++){
    cout << FamilyName[i] <<endl;
}

return 0;
}

Or use dynamic memory allocation to read the number of family member first and then do the allocation:

int main()
{

int count;
cout << "Enter Number of Family Members" <<endl;
cin >> count;

auto FamilyName = new string[count];

for (i = 0 ; i < count ; i++){
        cout << "Enter Family Member's Name: " <<endl;
        cin >> FamilyName[i];
}
for (i = 0 ; i < count ; i++){
    cout << FamilyName[i] <<endl;

    delete[] FamilyName;
}

Hope this helps

Answer 2

You are not allocating any memory to your string array, on this line string FamilyName[x]; // Array of Names string FamilyName[x]; // Array of Names x is not defined. It also may be a good idea to set a max array size or have some way of pushing on to the end of the array.

Answer 3

The size of your array should be constant.

Maybe use a vector of strings since vectors can grow dynamically.

string name;
vector<string> FamilyName;
for(int i = 0; i < x; i++)
{
    cin >> name;
    FamilyName.push_back(name);
}

Either that or give your array a constant size larger than any family size you might encounter.

string FamilyName[100];

if you wouldn't ever get a family with over 100 members.

Answer 4

You need to either allocate reasonable memory for FamilyName or use STL:

string[] FamilyName;
//after get x
FamilyName = new string[x];

or

vector<string> FamilyName;
cin << temp_string;
FamilyName.push_back(temp_string);